In a wafer level Si-Photonics test, a fiber array needs to touch the wafer surface to get the distance zero position. At the fiber array distance zero position, the fiber array may move up to 10 micrometer (μm) by the nano-positioner. A capacitance sensor records the distance 10 μm position and the sensor ensures that the wafer level test is being performed at the recorded distance position of 10 μm. However, during the fiber array touch down to the wafer surface, there is a potential risk of damage on the wafer or the fiber array due to the contact force. This requires a minimum contact area.
A known Si-Photonics device test includes a single fiber, which can be used to do optical test on Si-Photonics device and together with radio frequency (RF) and direct current (DC) measurement. However, single fiber tests have very low throughput and during the test there is a high risk of damage on the wafer and fiber array when the single fiber touches the pad, due to the small contact area. For example, a fiber array typically has a big contact area, e.g., 2 millimeter (mm) by 5 mm or 10 mm squared (mm2) (VT (thickness)×VW (width)). Consequently, it blocks the touch-down of the DC and RF probe tips.
Further, on a Si-Photonic device, there are grating couplers, DC probing pads and RF probing pads. The spacing between the grating couplers and the electrical probing pads is much smaller than that of the bottom area of a known fiber array, e.g., 500 μm. Due to the dimensions and construction of existing fiber arrays and the layout of the pads on the wafer, it is impossible to use the existing fiber array to perform optical, electrical and RF tests at the same time.
A need therefore exists for methodology enabling formation of a fiber array with a smaller contact area to allow optical, DC and RF mixed signal tests to be performed at the same time and the resulting device, that allows for a high throughput and that minimizes potential contact pad damage.